#include <iostream>
#include <cmath>
using namespace std;

int main()
{
	int n;
	cin >> n;
	
	int num = 1;
	int cnt = 0;
	
	while(true)
	{
		int theSquare = num*num;
		if(theSquare <= n)
		{
			cnt++;		
		}
		else
		{
			break;		
		}		
		num++;
	}
	cout << cnt << endl;
	return 0;
}
